Several human prostatic acid phosphatase isozymes have been purified and partial amino-terminal sequences determined. The purified proteins will be subfragmented by chemical and enzymatic cleavage, and amino acid sequences of purified peptides will be determined. Some of antigenic peptides such as loop peptides of human LDH-A and LDH-B as well a mouse LDH- C proteins will be chemically synthesized, and they will be used to raise monoclonal antibodies in order to study the antigenic structure of LDH proteins. The collaborative protein sequencing and peptide synthesis established with the University of North Carolina, Chapel Hill will also provide research services to other scientists of the Division of Intramural Research at the NIEHS.